Full scale measurements of the aerodynamic forces of trailers on flatcars have been performed at the Transportation Test Center in Pueblo, Colorado. These measurements were performed by mounting the trailers on the flatcar through force balances. In the two configurations that were tested the flatcar in front of the test car was loaded and unloaded. The tests were quite successful and resulted in consistent reproducible results. In addition to the full scale tests, wind tunnel tests were performed at Reynolds numbers up to 20% of full scale values for the same configurations. These wind tunnel tests supplemented previous wind tunnel tests similar to those previously reported in Volume I of this series. Reasonable agreement, to about 20%, was found between the wind tunnel and full scale tests. This agreement was about as good as between the wind tunnel tests themselves. Rolling resistance was also determined from the full scale tests as the difference between total and aerodynamic resistance. The results were degraded by hysteresis in the coupler force measurement but show good agreement with the Davis relation.

Supplemental Notes:

Prepared for U.S. Department of Transportation, Federal Railroad Administration, Office of Research and Development, Washington, D.C.